Removable electric terminal mounting



Oct. 4, 1966 JURCA REMOVABLE ELECTRIC TERMINAL MOUNTING Filed Sept. 17, 1965 United States Patent 4 Claims. (ill. 339-198) In various types of electrical equipment it is found desirable to provide for a removable mounting of electric conductor terminals, as for the purpose of adding and subtracting certain of the terminals depending on the particular conditions of use of the equipment concerned. It is known for such purposes to provide a fixed terminal supporting member in the form of an elongated profiled element of uniform, recessed, generally C-shaped cross section, into which a plurality of terminal members are withdrawably inse-rtable side by side along the length of the elongated support recess. The present invention is concerned with an improved construction of the removable terminal members used in such arrangements.

Objects of the invention include the provision of a removable terminal member of the elastically-engageable or snap-action type, which Will be of simplified, economical construction, robust, longlived and eflicient and convenient to use.

According to the invention, a removable terminal member for withdrawable insertion into a recess of a cooperating terminal supporting member, comprises a body having terminal means thereon, and a generally C-shaped springstrip having a midpoint thereof secured to said body with the concave side of the strip being directed away therefrom, said strip being formed to a general curvature that increases progressively from one to the other end and being dimensioned for forcible insertion, concave side foremost, into the recess of the supporting member, said body having outwardly directed bearing surfaces seatable in the fully inserted condition of said strip against cooperating outer bearing surfaces of the sup porting member positioned towards opposite ends from said midportion of the strip.

As will be more clearly understood from the detailed description later given, with the arrangement above described the lower-curvature end (or larger curvatureradius end) of the strip can be engaged with one of the two edges of the C-shaped recess, and the strip can then be pivoted about the engaged end thereof so as to force the opposite, greater-curvature end past the opposite side edge of the C-recess, thereby increasing the flexure of the strip and ensuring its firm elastic retention in its engaged position within the recess. The spring reaction force developed by the flexed strip in this condition acts to apply the bearing surfaces of the terminal body against the cooperating bearing surfaces of the supporting member to ensure accurate relative positioning between the terminal body and the supporting member.

Preferably one of the bearing surfaces of the body is positioned directly adjacent the low-curvature end of the strip while the opposite bearing surface is positioned intermediate the midportion of the strip and the highcurvature end thereof.

Preferably also, the supporting member is of the type in which the two legs of the C are unequal in length, so that the edges of the recess therein lie in difierent parallel planes, and the C-strip of the terminal body of the invention is dimensioned so that its larger-curvature end is engageable with the edge associated with the shorter leg of the C-recess of the supporting member.

The means securing the midportion of the C strip to the terminal body may comprise a cross member forming part of said body and positioned on the concave side of the C-strip, and a pair of stop elements secured to the C-strip on the concave side thereof and engaging opposite side surfaces of the cross member. At least one of said stop elements may be provided as a narrow strip punched out of the material of the C-strip and bent outwards from the general surface thereof towards the concave side. In one construction, the stop element nearer the lower-curvature end of the C-stn'p is provided as the punched-out strip just described, while the other stop element is provided as a separate element, such as a small cylindrical part made of electrically-insulating, somewhat resilient, material, forcibly retained in the concavity of the higher-curvature end of the C-strip.

Preferably, the lower-curvature end of the C-strip which is first engaged with the associated edge of the recess in the supporting member, is provided with an outwardly bent end portion to facilitate such engagement during the subsequent pivoting of the C-strip.

An exemplary embodiment of the invention will now be described for purposes of illustration but not of limitation with reference to the accompanying drawings, Where in:

FIGURES 1a, 1b and 1c are cross sectional views illustrating a removable terminal assembly according to the invention during successive stages of movement of the terminal member into engagement with the supporting member.

FIGURE 2 is an end view of the terminal member as seen on the arrow II in FIGURE 1a.

FIGURE 3 is a perspective View of the resilient C- strip; and

FIGURE 4 is a cross sectional view of part of a modified construction of the terminal member of the inventron.

In the embodiment shown the supporting member comprises a sectional element 3 of generally C-shaped cross section, having side flanges 3a, 3b of unequal length, flange 3a being longer than 3b, said side flanges being followed by inturned side edges or lips 9, 10 respectively, defining the edges of the recess within the member 3.

The terminal member of the invention adapted for withdrawable snap-action insertion into the recess of member 3, comprises a body 2 and a C-shaped spring strip 1 secured thereto. The terminal body 2 essentially comprises in the present example a one-piece moulding of insulating material including a pair of parallel spaced flanges 4 interconnected by a cross-member 5 of rectangular cross section near the end of the body on which the C-strip 1 is mounted. The ends of said flanges surrounding the cross member 5 are somewhat narrowed and wedge-shaped as shown, the width at the base of these portions corresponding to the entrance width of the recess defined between the side edges of the supporting member 3. Beyond both ends of the narrowed wedge-shaped portions the flanges 4 are formed with flat outwardly directed bearing surfaces 7, 8 which in the engaged position of the terminal member (see FIGURE 1c) are adapted to seat against the cooperating bearing surfaces provided at the outer sides of the lip portions 9, 10 of the supporting member 3.

The construction of the electric terminal associated with body 2 is immaterial to the present invention. As shown, the flanges 4 of the body are interconnected, in addition to the cross member 5, by spaced portions 22 which are recessed to receive respective screws 11 serving to secure a conductive strip 12 across the portions 22. Conductors are adapted to be connected by way of strip 12 through attachment to the screws 11. Strip 12 is retained in position by further webs 21 provided across the flanges 4.

Spaced inner surfaces 14, respectively of the spaced portions 22 serve as abutment means for the rear convex surface of the C-shaped strip 1.

The C-shaped spring strip 1, made of suitable spring steel, is formed with a curvature which increases progressively from one of its ends 1a to its other end 1b. That is, end 1a is formed with a relatively large radius of curvature, being almost flat, while end 1b is rounded to an arc of relatively small radius. The low-curvature end 1a is formed with an outwardly bent end part or lug 23. In the mid-area of the strip 1 a narrow central portion is punched out as at 25 and cut to form a tongue 18 at the base portion, which is deformed to stand protuberant in the concavity of the strip 1, the length thereof being such that the tip of tongue 18 will engage a side of the cross member 5 of body 2. On the opposite side surface of cross member 5, there is provided another abutment member in the form of a short cylindrical stud 24, e.g. of resilient plastic material, inserted between the flange portions 6 into the small-radius end are of the strip 1 and held thereby resiliently applied against member 5.

With this arrangement, to attach the spring strip 1 to the body member 2, the rounded end 1b of the strip is engaged inwardly (to the right in the drawings) of cross member 5 so that the tongue 18 engages with its tip the underside of the cross member, and the stud 24 is then forced into the rounded end 1b between the inner surface of the strip and the upper side of cross member 5, whereupon the stud will snap into its proper position of its own accord. The C-shaped strip 1 will thereafter be retained elastically in position with a certain amount of freedom both longitudinally between tongue 18 and stud 24, and in a direction normal to the strip surface between cross member 5 and the rear abutting surfaces 14, 15.

It will be noted that once the spring strip 1 has thus been inserted in position on body member 2, it will be practically impossible to remove it from the body member without damage, since this can only be done by means of a tool which will have to deform the strip 1 a greater amount to permit withdrawal of the stud 24 than for its insertion.

For engaging the terminal assembly thus obtained with the recessed support 3, said terminal assembly is first positioned in the manner shown in FIGURE la. The end lug 23 is engaged past the inner edge surface of the lower flange or lip 10, while the outer surface of the highercurvature end part 1b of the strip is engaging the outer surface of the upper lip 9. In this position, shown in FIG- URE 1a, the strip 1 is of course undeformed. It is then simply necessary to press the upper part of the terminal body 2 leftward according to the drawing in order to force the rounded upper end 1b of strip 1 past the lip 9 of member 3, while the strip 1 pivots around its lower end 1a as a fulcrum and the flexure of the strip 1 is increased, placing the spring strip under tension. When pressure is exerted upwardly on the upper part of the terminal body 2, lug 23 avoids escaping of the end 1b out of the recess of member 3. FIG. 2b illustrates an intermediate stage during this inserting step, and in that figure the initial shape of the strip 1 is shown in chain lines in' order to render apparent the gradual elastic deformation of the strip. The narrow wedge-shaped flange parts 6 of the terminal body enter the recess between the lips 9 and 10, and as the strip 1 snaps to its final position (shown in FIGURE 10) the bearing surfaces 7 and 8 seat against the mating outer surfaces of the lips 9 and 10 of support member 3, determining the correct final position of the body member 2 relative to the sunnort member.

Due to the relatively narrow transverse width dimension of the terminal assembly a number of such assemblies (depending of course on the length of the recessed supporting member 3) can thus be inserted side by side.

In the final condition shown in FIGURE 10, the spring strip 1 is clamped obliquely between the inner ends of the lips 9 and 10, and develops an elastic force which generates the oblique reaction forces F1 and F2 at its points of engagement with said lips. The tension in the spring strip, tending to restore it to its initial general curvature, creates a force F3 which balances the resultant of the reactions F1 and F2 and acts to press the strip against the cross member 5, thereby exerting on the terminal assembly a leftward force applying the bearing surfaces 7 and 8 against the mating outer surfaces of the lips 9 and 10. The spring force necessary to produce the requisite change in curvature in the strip 1 (i.e. the force F3 retaining the terminal in mounted position) depends in part on the inherent resiliency of stud 24. With said stud being made from substantially rigid material, the positioning force is greater, but the dimensional tolerances in the assembly are correspondingly reduced.

In the modified construction shown in FIGURE 4, the spring strip 1 is provided in the form of a pair of internested strip elements 1A and 1B, with only the outer strip element 1B being formed with the end lug 23. Both strip elements are formed with the central cutouts such as 25, and'the tongue 18b of the outer element 1B is inserted into the cutout 25 of the inner strip element 1A. The composite strip shown in FIGURE 4 may be used when desired to provide an increased spring constant.

For withdrawing a terminal assembly 21 from out of the supporting member 3, the procedure is the reverse from that described for insertion, member 2 being pulled outwards (i.e. rightwards) and downwards to force the end 1b of the strip past the lower surface of the lip 9 to the position shown in FIGURE 1a, whereupon the lower end 1a of the strip 1 can be easily removed past the lip 10.

It will be evident that various modifications may be made in the structure illustrated and described without exceeding the scope of the invention.

What I claim is:

1. A terminal member for withdrawable insertion into the longitudinal groove of a C-shaped terminal supporting section having flat, parallel lips, the one depressed with respect to the other, comprising a body having a pair of parallel projecting flanges for transverse engagement into said groove, a cross-member between said flanges, and outwardly directed bearing surfaces seatable in the fully in serted position of said body against said lips; terminals carried by said body; and a generally C-shaped spring strip having from the midportion thereof one end of low curvature engageable with said one depressed lip and another end of high curvature forcibly engageable with said other lip, said strip further having a tongue stamped out of one said end near the midportion of the strip, directed from said end to said midportion and pressed outwards towards the concave side of the strip, said midportion of the strip engaging by its concave face an inner surface of said cross-member and the tip surface of said tongue engaging a corresponding side of said cross-member.

2. A terminal member according to claim 1, further comprising a substantially cylindrical block resiliently engaged between the concavity of said high curvature end and the corresponding side of the cross-member.

3. A terminal member according to claim 1 wherein the p f said 19W curvature end of the strip is outwardly bent 5 with respect to the general C-curvature of the strip and wherein the distance between said outwardly bent tip and the adjacent one of said outwardly directed bearing surfaces is greater than the thickness of said depressed lip, thereby providing a space for reception of said lip therewithin.

4. A terminal member according to claim 1 wherein the tip of said low curvature end of the strip is outwardly bent with respect to the general C-curvature of the strip thereby providing a lug insertable into said groove of the terminal supporting section :to a position in back of and in interfering relation to the latters said depressed lip to avoid escape of the low curvature end of the strip from the terminal supporting section.

References Cited by the Examiner 5/1959 Germany. 7/1958 Great Britain.

EDWARD C. ALLEN, Primary Examiner.

ALFRED S. TRASK, Examiner. 

1. A TERMINAL MEMBER FOR WITHDRAWABLE INSERTION INTO THE LONGITUDINAL GROOVE OF A C-SHAPED TERMINAL SUPPORTING SECTION HAVING FLAT, PARALLEL LIPS, THE ONE DEPRESSED WITH RESPECT TO THE OTHER, COMPRISING A BODY HAVING A PAIR OF PARALLEL PROJECTING FLANGES FOR TRANSVERSE ENGAGEMENT INTO SAID GROOVE, A CROSS-MEMBER BETWEEN SAID FLANGES, AND OUTWARDLY DIRECTED BEARING SURFACES SEATABLE IN THE FULLY INSERTED POSITION OF SAID BODY AGAINST SAID LIPS; TERMINALS CARRIED BY SAID BODY; AND A GENERALLY C-SHAPED SPRING STRIP HAVING FROM THE MIDPORTION THEREOF ONE END OF LOW CURVATURE ENGAGEABLE WITH SAID ONE DEPRESSED LIP AND ANOTHER END OF HIGH CURVATURE FORCIBLY ENGAGEABLE WITH SAID OTHER LIP, SAID STRIP FURTHER HAVING A TONGUE STAMPED OUT OF ONE SAID END NEAR THE MIDPORTION OF THE STRIP, DIRECTED FROM SAID END TO SAID MIDPORTION AND PRESSED OUTWARDS TOWARDS THE CONCAVE SIDE OF THE STRIP, SAID MIDPORTION OF THE STRIP ENGAGING BY ITS CONCAVE FACE AN INNER SURFACE OF SAID CROSS-MEMBER AND THE TIP SURFACE OF SAID TONGUE ENGAGING A CORRSPONDING SIDE OF SAID CROSS-MEMBER. 